1. Technical Field
The present disclosure relates to an optical element, a transmission probe, a sample container, an optical device, and an immersion transmission measurement method.
2. Description of the Related Art
A transmission probe is used when the light absorption characteristics, the transmission characteristics, and the like of a solution are measured. The transmission probe has a function of applying light from a light source to the solution, and a function of reflecting light having passed through the solution to return the light. In immersion transmission measurement using the transmission probe, for example, a transmission probe (immersion probe) 300 is connected to a spectroscopy apparatus 310 via an optical transmission path 320 such as an optical fiber as illustrated in FIG. 11. The transmission probe 300 is immersed directly in a sample solution 340 in a sample container 330.
In terms of the optical transmission path 320, one optical path may be used to propagate both irradiation light and measurement light that has passed through the sample solution 340. However, the optical paths for the irradiation light and the measurement light are normally separated. Moreover, there are pre-spectroscopy in which light dispersed in advance is applied, and post-spectroscopy in which white light is applied and the measurement light is dispersed.
FIGS. 12A and 12B are diagrams illustrating configuration examples of known transmission probes. In the transmission probe of the type illustrated in FIG. 12A, the irradiation light passes through the sample solution once in one direction. In the transmission probe of the type illustrated in FIG. 12B, the irradiation light passes (reciprocates) through the sample solution twice. The transmission probe of the type illustrated in FIG. 12B is also called a transmission reflection probe (transflectance).
Both types of transmission probes have a rod-like shape to facilitate the immersion transmission measurements. A gap 307 that transmits light is formed on a side surface of each of the transmission probes. The sample solution enters the gap 307. These transmission probes include connectors 301 to be connected to the spectroscopy apparatus 310 via the optical transmission path 320, an irradiation purpose optical transmission path 302 that guides the irradiation light from the connector 301, a measurement purpose optical transmission path 303 that guides the measurement light to the connector 301, an optical system 304 such as a lens, windows 305 placed above and below the gap 307, and a reflector 306.
The prism reflector 306 is used in the type illustrated in FIG. 12A. A plane mirror as the reflector 306 is used in the type illustrated in FIG. 12B. In the type illustrated in FIG. 12B, light passes through the sample solution twice. Therefore, in a case of the same specification, the width (sample path) of the gap 307 in the transmission probe of the type illustrated in FIG. 12B is half the width of the gap 307 in the transmission probe of the type illustrated in FIG. 12A. Optical fibers and the like can be used as the irradiation purpose optical transmission path 302 and the measurement purpose optical transmission path 303.
A reference technique in this field is disclosed in, for example, JP-A-2009-250825.